Visual evoked potentials to checkerboard pattern were studies in normal volunteers and patients with various neurological disorders, particularly multiple sclerosis and seizures. A. Multiple Sclerosis: The prolongation of the major positive peak has been consistently found in patients with history of optic neuritis and in some patients even without such a history. In some patients with the history of optic neuritis who have been visually asymptomatic for many years, however, persistent prolongation or normalization of the latency has been noted. B. Epileptic Seizures: Visual evoked potentials to be a half-visual field stimulation (studying the retrodiasmatic visual pathway) have been studied in patients with complex partial seizures. The primary goal is to predict the side of the epileptic lesion by the visual evoked potentials. The preliminary analysis in 6 patients showed no clear-cut predictability. C. Other Neurological Disorders: Visual evoked potentials were studied in a patient with Shapiro syndrome who has paroxysmal hypothermia. When the body temperature dropped to 33-34 degrees C, the latency of the major positive peak was significantly prolonged, whereas with normal body temperature (35-36 degrees C), the latencies were normal. The significance of the visual evoked potentials lies in the fact that they are totally noninvasive, are useful in detecting the occult lesions and in evaluating the visual system in the context of the cortical nervous system integrity.